1. Field of the Invention
The present application generally relates to compositions for coating metallic components, and in particular, relates to thermal barrier coatings that can be used for aircraft engine components.
2. Description of the Related Art
Thermal barrier coatings are commonly applied to aircraft engine components and other metallic parts that operate at elevated temperature conditions. The coatings insulate the aircraft engine components from heat, thus allowing the components to operate under higher temperatures, which in turn can improve engine efficiency. Thermal barrier coatings also protect the engine components, such as turbine blades and combustion chambers, from oxidation and thermal fatigue that may be caused by prolonged thermal exposure. For example, yttria modified zirconia is commonly used as a thermal barrier coating because of the favorable heat insulating properties of zirconia. While a number of different thermal barrier coating materials have been developed for aircraft engine components, there is a continuing need for coatings that are stable at higher temperature conditions.
For military aircrafts, it may also be desirable to apply a radio frequency (RF) absorber material on the engine components to evade radar detection. A layer of RF absorber such as Ferrite 50 or TT2-111R, available from Trans-Tech Inc. of Adamstown, Md., is often applied to the turbine blades in addition to the thermal barrier coating. However, the additional layer adds weight to the aircraft and requires an additional manufacturing step. As such, there is a need to find an effective thermal barrier coating that can operate at higher temperature conditions and there is also a need for reducing the layers of coating on aircraft engine components.